In facilities handling large amounts of flammable materials, explosives, and hazardous materials such as a chemical plant, an oil refinery, and a power plant, it is important to prevent a serious accident by detecting corrosion and thickness reduction of pipes and tanks at an early stage.
To this end, an abnormality detection system including a distributed temperature sensor (DTS) using an optical fiber as a temperature sensor is employed in some cases.
In such an abnormality detection system, the optical fiber is laid around, for example, pipes and tanks, and an end portion of the optical fiber is connected to the distributed temperature sensor. Then, laser light is emitted from the distributed temperature sensor into the optical fiber, and Raman scattered light occurring in the optical fiber is detected by the distributed temperature sensor to obtain the temperatures of the pipes, tanks, and the like. The presence or absence of an abnormality is determined based on the obtained results.
In facilities such as a chemical plant, an oil refinery, and a power plant, delay of abnormality detection may lead to a serious accident. Accordingly, there is a demand for a system which may detect occurrence of an abnormality at an earlier stage.
Note that techniques relating to the present application are disclosed in Japanese Laid-open Patent Publication No. 09-18428, Japanese Laid-open Patent Publication No. 2003-232013, Japanese Laid-open Patent Publication No. 06-273644 and International Publication Pamphlet No. WO 2010/125712.